Decay rates of organophosphate residues in the fleeces of sheep dipped for flystrike control

Rammell, C. G.; Bentley, Gordon

doi:10.1080/00288233.1989.10423456

Cited by 6 publications

(2 citation statements)

References 5 publications

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“…There were some differences in OP and SP residues between states that could be due to differences in the amount applied or in breakdown rate or both. However, these differences were not always consistent with the assumption that breakdown should be faster in hotter areas (Rammell and Bentley 1989), and the differences were small compared with the overall variation. State differences were not included in the final analysis.…”

Section: Differences Between Statesmentioning

confidence: 64%

Modelling pesticide residues on greasy wool: using organophosphate and synthetic pyrethroid survey data

Plant¹,

Horton²,

Armstrong³

et al. 1999

Aust. J. Exp. Agric.

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Summary. Several surveys have examined the relationship between organophosphate and synthetic pyrethroid residues in wool and associated treatments. These have been combined and summarised using a model of on-farm survey data. The model estimated the amount of chemical taken up by the wool at application. This was based on experimental breakdown rates of these pesticides on wool determined in controlled trials. For about 10% of survey results the chemical measured on the wool did not match the chemical the producer said was applied. A further 5% of results were excluded because the amount of chemical detected on the wool was inconsistent with the stated time of treatment and shearing. With the remaining results there was a very high variation in residues resulting from the same (stated) treatment. It is clear that many producers do not know what chemicals they have used or how much they applied. The wide variation in results suggests that some producers may apply excessive amounts of pesticides while others use too little to have a useful effect. The model estimated the amount of pesticide taken up by the fleece using the residue left at shearing and the known breakdown rate for a given method and chemical group. When organophosphates were applied by dipping, the amount of chemical taken up by the fleece appeared to increase as the length of the wool increased. This was generally higher than would be anticipated from label dose rates but was consistent with the stripping characteristics of these chemicals. Therefore dipping as soon as possible after shearing left much lower residues (<10 mg/kg wool) than delayed treatment (often 10–30 mg/kg wool). In contrast the survey results suggest that the amount retained by sheep as a result of jetting decreased in longer wool. Jetting treatment rates appear to be lower than recommended, particularly for sheep with more than 6 months wool. Therefore jetting (as used by producers) left much lower residues in wool than dipping (with similar length wool) and was usually only above 10 mg/kg wool if carried out in the last 5 months before shearing, or if the same sheep received repeated treatments. The residue of synthetic pyrethroid retained in the fleece after dipping or long wool backliner application increased as the length of the wool increased at treatment, and appeared generally consistent with label recommendations. Current long wool backline products usually left residues of synthetic pyrethroid above 10 mg/kg on the wool. Short wool dipping left less than 10 mg/kg wool while off-shears backliners usually left average residue concentrations of about 2 mg/kg wool. Although the actual on-farm results vary 4-fold above and below the average, the model can be used to estimate the expected residue concentration and likely range of results from most standard on-farm organophosphate and synthetic pyrethroid treatments. This will allow improved provision of advice so that most producers can meet specified industry standards. It will allow wool buyers to estimate the risk of purchasing high residue wool based on producers’ statements about treatments applied.

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Section: Differences Between Statesmentioning

confidence: 64%

Modelling pesticide residues on greasy wool: using organophosphate and synthetic pyrethroid survey data

Plant¹,

Horton²,

Armstrong³

et al. 1999

Aust. J. Exp. Agric.

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“…Some experiments on photodegradation rates of organophosphorus insecticides in wool have been undertaken, but no degradation products were identified (1). The same authors also mentioned from earlier studies that insecticides dissipated from sheep more rapidly during summer as compared to winter conditions, which was presumably attributed to sunlight and summer heat (2).…”

Section: Introductionmentioning

confidence: 98%

Photolysis Experiments on Phosmet, an Organophosphorus Insecticide

Sinderhauf

Schwack

2003

J. Agric. Food Chem.

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The organophosphorus insecticide phosmet is used in plant protection as well as against parasites on animals. Phosmet showed numerous photoinduced reaction pathways, which first were studied in the presence of model environments for animal fur lipids (e.g., wool wax). The model solvents for saturated and unsaturated lipids were cyclohexane and cyclohexene, whereas methanol and 2-propanol were used as models for primary and secondary alcohol moieties of lipids. The measured degradation rates over an irradiation period of 7 h in all solvents used were very similar (49-55%). The obtained photoproducts generally included phthalimide, N-hydroxymethylphthalimide, and N-methoxymethylphthalimide. Furthermore, depending on the solvent used, additional degradation products were detectable as N-isopropoxy- and N-methylphthalimide in the presence of 2-propanol and cyclohexene, respectively. However, in the presence of cyclohexene, despite the similar turnover, distinctly lower concentrations of photoproducts were found, indicating further still unknown degradation pathways. Irradiations in methanol with increasing percentages of water led to higher degradation rates; however, the products were found to be the same. Irradiation experiments with pure phosmet on silica TLC plates and glass surfaces resulted in degradation rates of 19 and 32%, respectively, after 6 h. The results obtained clearly demonstrate for the first time that the photoinduced degradation of phosmet is strongly dependent on the chemical environment, affecting less the turnover than the photoproducts formed. The results additionally demonstrate the need to investigate the degradation behavior of phosmet on wool and in the presence of wool wax.

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The organophosphate insecticide Coumaphos induces oxidative stress and increases antioxidant and detoxification defences in the green macroalgae Ulva pertusa

Schweikert

Burritt

2012

Aquatic Toxicology

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Decay rates of organophosphate residues in the fleeces of sheep dipped for flystrike control

Cited by 6 publications

References 5 publications

Modelling pesticide residues on greasy wool: using organophosphate and synthetic pyrethroid survey data

Modelling pesticide residues on greasy wool: using organophosphate and synthetic pyrethroid survey data

Photolysis Experiments on Phosmet, an Organophosphorus Insecticide

The organophosphate insecticide Coumaphos induces oxidative stress and increases antioxidant and detoxification defences in the green macroalgae Ulva pertusa

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